Robert Colvile is a writer and senior comment editor at the Telegraph, who cares more about politics and policy than is probably healthy - for his newest pieces, please see here. He tweets as @rcolvile.

Ed Llewellyn: Will David Cameron draw a line in the sand?

So, the pack has the scent of a fresh kill – John Yates has admitted that Ed Llewellyn, David Cameron's chief of staff, was the "senior Downing Street official" who apparently warned Scotland Yard not to tell the Prime Minister about Neil Wallis's appointment, for reasons of deniability. This after Llewellyn also failed to pass on warnings from the Guardian about Andy Coulson's fitness for office.

Suddenly, Mr Llewellyn has become the story – but hold on a minute. What John Yates actually said was that he offered to brief Mr Llewellyn (rather than the Prime Minister) on what exactly the technical terms involved meant, ie what the exact scope of the inquiry would be. I don't have the transcript in front of me, but I recall that Yates said that was entirely proper and he didn't have a particular problem with it.

Llewellyn obviously has questions to answer – in particular if it turns out that he did indeed warn the Met off – but I suspect David Cameron will need far more of a smoking gun before he throws such an important member of his team to the wolves. After all, thus far, throwing a piece of meat to them has only served to whet their appetite.

UPDATE: According to James Forsyth (via @Spectator_CH), No 10 are "offering robust–and immediate–support to Ed L. Promise to publish emails between him and Yates." See what I mean?